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While what happened in Aurora, Colorado may never make sense to us, there are some common connections with mass shooters. San Diego psychiatrist Clark Smith M.D. has worked on several high profile cases and shares his opinions with NBC 7s Tony Shin. Get more coverage in our special section "The Dark Knight" Massacre
(Published Saturday, Jul 21, 2012)

Updated at 9:09 AM PST on Tuesday, Jul 24, 2012

Moviegoers are on edge and police departments on high alert after last week's Batman movie massacre. At least three suspicious moviegoers were arrested and more ejected after at least six suspicious incidents at theaters across the United States.

Those incidents at screenings of "The Dark Knight Rises" have already-skittish audiences now even more jittery at the prospect of a possible copycat crime.

Colorado Shooting Impact on Movie Industry

It's not clear just how much impact the Colorado theater shooting will have on the movie industry and the box office. Janet Kwak reports for the NBC4 News at 11 p.m. on Friday, July 20, 2012. (Published Saturday, Jul 21, 2012)

Witnesses said he held his cell phone in the air and yelled, "I should go off like in Colorado," before asking, "Does anyone have a gun?" After unnerved patrons alerted theater security, cops arrested him for making criminal threats — a felony if he is charged — but found no weapons on him, in the theater or in his home, NBC Los Angeles reported.

Police told The Star-Ledger that the man spoke to somebody outside the door and returned to his seat — but didn't come forward when police asked him to. The movie was cancelled, and 100 customers were given refunds.

In Arizona, moviegoers panicked and fled a theater when a drunk homeless man who was disrupting a screening and intimidating them suddenly grabbed for his backpack. Authorities said the backpack contained an empty alcohol container and half a bottle of liquor.

Patrons in a theater near Pittsburgh panicked and fled, too, after a fight broke out during the movie between two other moviegoers.

What could have been the most tangible threat linked to the "Dark Knight Rises" shooting took place nowhere near a movie theater.

Police in Maine stopped a man for speeding and found an AK-47 assault rifle, four handguns, ammunition and news clippings about the Aurora, Colo., massacre in his car.

The man, Timothy Courtois of Biddeford, Maine, said he had seen the Batman movie a day earlier — and carried a gun into it — and was on his way to shoot a former employer. Cops later found other guns, including a machine gun, and thousands of rounds of ammunition in his home, and he was charged with speeding and possessing a concealed weapon.

"We don't know what his true intentions were," a Department of Public Safety spokesman told The Associated Press, adding that the Federal Bureau of Investigation and the Bureau of Alcohol, Tobacco and Firearms was aiding its investigation.

In the wake of the Friday morning shooting in Colorado, local police departments have stepped up their patrolling of movie theaters to ease public fears and deter would-be copycats.

Theaters have tightened their security measures, too, and AMC Theatres has barred patrons from wearing face-concealing masks or bringing fake weapons into its theaters.